Abstract CT404: Phase I/II study of VAL-083 in patients with recurrent glioblastoma multiforme

Abstract

Abstract Median survival for patients with recurrent glioblastoma multiforme (GBM) is less than 6 months. Front-line systemic therapy is temozolomide, but chemo-resistance due to O6-methylguanine-DNA-methyltransferase (MGMT) activity has been implicated in poor outcomes. VAL-083 is a structurally unique bi-functional DNA alkylating small molecule drug that crosses the blood-brain barrier and accumulates in brain tumor tissue. Previous human clinical studies by several investigators have suggested that VAL-083 has anti-tumor activity against a broad range of tumor types including GBM. In preclinical in vitro studies, VAL-083 demonstrated activity in a wide range of cancer cell lines, including pediatric and adult GBM cell lines and GBM cancer stem cells. Notably, due to crosslink formation on N7 of guanine, VAL-083 overcomes chemo-resistance to MGMT in vitro. In light of extensive safety data from several clinical trials and promising efficacy signals in CNS tumors, DelMar initiated a new clinical study to determine the safety, tolerability, pharmacokinetics, anti-tumor activity in patients with recurrent GBM. This is an open-label, single-arm Phase I/II dose-escalation study in patients with histologically-confirmed initial diagnosis of malignant GBM. The study utilizes a 3+3 dose-escalation design. Patients receive VAL-083 i.v. on days 1, 2, and 3 of a 21 day cycle. GBM patients have previously been treated with surgery and/or radiation, if appropriate, and must have failed both bevacizumab and temozolomide, unless contraindicated. In the ongoing trial, cohorts 1 through 4 (10 mg/m2) have completed the trial successfully with no drug-related serious adverse events (SAEs), and maximum tolerated dose (MTD) was not yet reached. Enrollment for Cohort 5 (20 mg/m2) has been initiated. Pharmacokinetic analyses show dose-dependent increase in exposure with a short 1-2 hour plasma half-life and a Cmax of <200 ng/ml at 10 mg/m2. Historical data suggests a long half-life in the cerebrospinal fluid (CSF) (>20 hours) with preferential accumulation to brain tumor tissue. MGMT status of patients and drug concentration in the CSF are being evaluated when possible. ClinicalTrials.gov Identifier: NCT01478178 Citation Format: Kent C. Shih, Manish R. Patel, Jeffrey Bacha, Dennis M. Brown, William J. Garner, Anne Steino, Richard S. Schwartz, Sarath Kanekal, Mike Li, Lorena M. Lopez, Howard A. Burris. Phase I/II study of VAL-083 in patients with recurrent glioblastoma multiforme. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr CT404. doi:10.1158/1538-7445.AM2014-CT404